Copper Electroplating part 1 (building the tank)

When prototyping even small boards at home, dealing with a lack of plated through holes (PTH) is always aggravating. Whether it involves special layout considerations so that you’re not making connections under components (where you can’t get a soldering iron) or spending extra time hand soldering each and every via – not having plated through holes on the PCB’s made at home is a pain. This guide covers how to setup a simple and inexpensive PTH process.

We’re going to embark on a journey with the goal of creating boards with PTH at home. Professional board houses use a few different process tanks (chemical baths) to accomplish this, we’ll try and limit our approach to just one, with some mechanical preparation.

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This build is based loosely from plans you can find from Think and Tinker. We’d like to thank Think and Tinker for the many guides they’ve posted – without them, this build wouldn’t be possible. We’re doing quite a number of things differently (and non-otimally, according to their instructions) based on readily available materials. We’d expect better results if we were to follow their plans more closely.

If you’re the visual type, feel free to check out the image gallery fo this project:

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Fabricating the Plating Tank

The plating tank consists fo the following materials:

1 gallon plastic container (with handle and lid)

1/4″ copper pipe

12 AWG solid core copper wire

1

Cut the copper pipe to length and straighten it out, drilling a hole in one side (the 12 gauge wire will go through this hole later)

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2

We’ll be making two rows of anodes out of the copper pipe. We’re spacing each section of pipe every 1.5″ or so.

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3

Solder the pieces of pipe onto the copper wire

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4

Cover the tops of the wire and tubing with hot glue. The hot glue will help to protect the copper from gasses in the plating solution, whcih will cause erosion. A propane torch can be used to melt the glue, instead of a standard (wimpy) hot glue gun. Be careful, you can very easily melt the solder if you’re not careful (afterall, these are meant for soldering pipes together)!

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5

Drill holes in the plating tank where you’d like to locate the anodes. Ideally, these would be placed about 3 inches away from center (on each side), but our tank wasn’t big enough.

Our conductive ink includes simply waterproof ink and graphite powder. The idea is that the ink/graphite coat the inside of the through holes, making them conductive. When current passes through the anodes and into our PCB (the cathode), the copper in the solution will coat the cathode. But, if there’s no curent flowing into the surface on the cathode, it won’t get coated. Of course, the ink needs to be waterproof so it won’t run when placed into the plating solution. It’s primarily used as a carrier to get the graphite to stick to the through hole walls.

We’ve purchased our graphite from ebay, trying to find the smallest particles we could – to make it go into solution more easily.

To make the conductive ink, add around 10 grams of graphite to the 1 oz of ink (the pictuer shows 5 grams, this was later doubled). {gallery link=electroplating1 index=22}{/gallery}